Thermostatic valve



FIG. 1 is a front elevation view of a thermostatic valve showing the new design;

FIG. 2 is a front, top, and left side perspective view thereof, wherein the opposite side perspective view is a mirror image;

FIG. 3 is a right side elevation view thereof; and,

FIG. 4 is a top plan view thereof.

The broken lines shown in the drawings illustrate portions of the thermostatic valve that form no part of the claimed design. 

CLAIM The ornamental design for a thermostatic valve, as shown and described. 